SMALL FUUITS 161 



the mycelium of a fungus which has been held responsible 

 for the damage to the plant although conclusive proof of its 

 causal relation to the disease has not yet been adduced. 



Little can be suggested in the waj^ of treatment. It is, 

 however, best to pull up and burn affected plants, and it 

 is inadvisable to place susceptible crops upon soil which 

 is known to be diseased. 



GRAPE 



Black rot (Guignardia Bidwellii (Ell.) V. & R.). — 

 This widespread and exceedingly destructive disease has 

 been responsible for the abandonment of grape raising in 

 many sections of the country. It is found in all sections 

 to greater or less extent. In 1906 in Michigan the loss from 

 black rot was estimated at 30 to 40 per cent of the crop; 

 in Ohio in 1905 at 30 per cent of the crop worth $95,000. 

 In many sections the loss is practically total unless measures 

 are taken to check its ravages. 



In its most familiar form the disease consists of spotting 

 and decay of the fruit. Black or brown spots, one or more 

 in number, at first infinitesimal in size, appear upon the 

 berry. The spots enlarge with great rapidity, one spot in 

 a few days encompassing the whole berry and changing it 

 into a black mass. As the rot progresses the skin remains 

 intact, and soon the berry begins to shrink and shrivel until 

 it is eventually merely a dry, hard, wrinkled, mummified 

 fruit. The rapidity with which this change takes place is 

 shown in the accompanjdng figure. Many of the berries so 

 mummified fall to the ground, others remain upon the vine. 



Upon the leaves the disease appears considerably earlier 

 than upon the fruits. Here it produces tan-colored spots 



